Move ScopedAddrinfo to libnetdutils

This is a preparation step for stopping include system/netd/include.

Bug: 135235267
Test: m
      cd system/netd && atest
Change-Id: Idfe5e25e8016881987c322b333ea37c502e5d7ca
diff --git a/libnetdutils/include/netdutils/InternetAddresses.h b/libnetdutils/include/netdutils/InternetAddresses.h
index 07a6e90..472ac89 100644
--- a/libnetdutils/include/netdutils/InternetAddresses.h
+++ b/libnetdutils/include/netdutils/InternetAddresses.h
@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 
-#ifndef NETDUTILS_INTERNETADDRESSES_H_
-#define NETDUTILS_INTERNETADDRESSES_H_
+#pragma once
 
+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdint.h>
 #include <cstring>
@@ -104,6 +104,16 @@
 
 }  // namespace internal_
 
+struct AddrinfoDeleter {
+    void operator()(struct addrinfo* p) const {
+        if (p != nullptr) {
+            freeaddrinfo(p);
+        }
+    }
+};
+
+typedef std::unique_ptr<struct addrinfo, struct AddrinfoDeleter> ScopedAddrinfo;
+
 inline bool usesScopedIds(const in6_addr& ipv6) {
     return (IN6_IS_ADDR_LINKLOCAL(&ipv6) || IN6_IS_ADDR_MC_LINKLOCAL(&ipv6));
 }
@@ -291,5 +301,3 @@
 
 }  // namespace netdutils
 }  // namespace android
-
-#endif  // NETDUTILS_INTERNETADDRESSES_H_